With the development of the communications network and the continuous progress of technologies such as computers and semiconductors, mobile terminals, such as smartphones and tablets, become popular rapidly, and become a primary means of communication between people. One user may have multiple intelligent terminals at the same time. Different mobile terminals have different functions, features, and application scenarios. A user may preferentially use different terminals in different application scenarios. For example, people generally use mobile phones on the road, and use portable computers or tablets at home.
With the continuous improvement of processing capabilities of mobile terminals, one terminal can process multiple tasks simultaneously. If a user has multiple mobile terminals at the same time, such as multiple mobile phones, or multiple switched network identifiers, such as multiple mobile numbers, the user generally expects to answer incoming calls of two mobile phones by using one mobile phone. A service provider provides a call roaming service in which a user can preset call roaming on a first terminal, and when another user of a remote terminal calls the first terminal, a switched network can make the call roam to a second terminal.
In the existing call roaming, the switched network implements roaming control over multiple mobile terminals. Therefore, support of the switched network is needed, and the multiple terminals that use the call roaming service should have both a capability of communicating with the switched network and a switched network identifier. Each roaming terminal needs to pay a roaming service fee to an operator to which the switched network belongs. Besides, in a place in which the switched network is not supported, the call roaming service cannot be used. Therefore, the existing call roaming service is inconvenient to use and has a high usage cost.